/Engine/Source/Developer/BSPUtils/Public/BSPUtils.h
Takes a list of polygons and creates a new list of polys which have no overlapping edges. It splits edges as necessary to achieve this.
static void polySplitOverlappingEdges ( [TArray](API\Runtime\Core\Containers\TArray)< [FPoly](API\Runtime\Engine\Engine\FPoly) > * InPolyList, [TArray](API\Runtime\Core\Containers\TArray)< [FPoly](API\Runtime\Engine\Engine\FPoly) > * InResult )